President Bill Clinton is due to see both Viktor Chernomyrdin and the US civil rights campaigner Jesse Jackson on Monday.

The Reverend Jackson, who secured the release of three US soldiers from captivity in Yugoslav, is to deliver a letter from President Slobodan Milosevic, in which the latter is understood to ask for a face-to-face meeting between the two presidents.

Stephen Sackur in Washington says there is new pressure on Mr Clinton to end the Kosovo confrontation quickly

Rev Jackson says the release of the three US POWs opens a diplomatic door.

And he said those who refused to talk ran the risk of losing moral authority.

Personal message

Moscow unexpectedly announced Mr Chernomyrdin's visit to Washington after Boris Yeltsin discussed the crisis with President Clinton by phone.

Viktor Chernomyrdin: Touring capitals

The envoy is understood to be taking with him a personal message from President Yeltsin.

Moscow Correspondent Robert Parsons says Russia is determined to stay at the centre of the diplomatic efforts to reach a peaceful solution to the Kosovo crisis.

Mr Chernomyrdin has been shuttling between Moscow, Belgrade and Western European capitals for in an effort to find a broker a peaceful solution to the Kosovo conflict.

Robert Parsons in Moscow says Mr Chernomyrdin was quietly optimistic after meeting Mr Milosevic

He said: "The current situation is far from simple, but it gives us hope that the efforts Russia has taken, and will take, are significant."

Mr Chernomyrdin visited Rome, Bonn and last week and has signalled his intention to visit London and Paris later this week.

He has not publicly discussed the results of his talks in Belgrade with Yugoslav President Slobodan Milosevic.

Russia condemns Nato air strikes against Yugoslavia but has been trying to find a way to end the bombing.

One major stumbling block has been Nato insistence that it leads any international peace-keeping force posted in Kosovo.

Yugoslavia opposes foreign troops on its soil.

But a US Congress team says it has secured agreement with a team of senior Russian lawmakers and an adviser to President Milosevic on a framework for resolving the Kosovo crisis.

Congressman Curt Weldon says the plan, drafted during two days of talks in Vienna, complies with Nato's conditions for stopping Operation Allied Force, and also takes into account Russian and Serbian concerns.